1. Field of the Invention
The present invention relates to a handle assembly for a medical robotic system.
2. Background Information
Historically, surgery has been performed by making large incisions in a patient to provide access to the surgical site. There has been developed instruments that allow a surgeon to perform a procedure through small incisions in the patient. The instruments include an endoscope which has a camera that allows the surgeon to view the internal organs of the patient through a small incision. Such procedures are less traumatic to the patient and have shorter recovery times than conventional surgical procedures. Endoscopic instruments have even been used to perform minimally invasive heart surgery. Blockage of a coronary artery may deprive the heart of blood and oxygen required to sustain life. The blockage may be removed with medication or by an angioplasty. For severe blockage, a coronary artery bypass graft (CABG) is performed to bypass the blocked area of the artery. CABG procedures are typically performed by splitting the sternum and pulling open the chest cavity to provide access to the heart. An incision is made in the artery adjacent to the blocked area. The internal mammary artery is then severed and attached to the artery at the point of incision. The internal mammary artery bypasses the blocked area of the artery to again provide a full flow of blood to the heart. Splitting the sternum and opening the chest cavity can create a tremendous trauma to the patient. Additionally, the cracked sternum prolongs the recovery period of the patient.
Computer Motion of Goleta, Calif. provides a system under the trademark ZEUS that allows a surgeon to perform a minimally invasive surgery, including CABG procedures. The procedure is performed with instruments that are inserted through small incisions in the patient's chest. The instruments are controlled by robotic arms. Movement of the robotic arms and actuation of instrument end effectors are controlled by the surgeon through a pair of handles and a foot pedal that are coupled to an electronic controller. Alternatively, the surgeon can control the movement of an endoscope used to view the internal organs of the patient through voice commands.
The incisions create pivot points for the medical instruments. The pivot points constrain movement of the instruments within the patient to four degrees of freedom; translation, pan, tilt and rotation of the instrument shaft. Additionally, the pivot point may cause a reverse movement of the instrument. For example, leftward movement of the system input handle may actually cause a rightward movement of the instrument. The surgeon must compensate for such constraints, thereby increasing the difficulty of using the system for performing a medical procedure.
It would be desirable to provide a robotic handle that gives the user the sensation of controlling the tip of the instrument. It would also be desirable to generally improve the ergonomics of medical robotic master handles.
There have been developed medical robotic systems that create six degrees of freedom for the surgical instruments. Six degrees of freedom requires relatively complex mechanism that increases the size and cost of the system. It would be desirable to provide an effective medical robotic system that would only require five degrees of freedom.